Back to EveryPatent.com
| United States Patent |
6,133,392
|
|
Utecht
, et al.
|
October 17, 2000
|
Insoluble polymers which can swell only slightly with modified amino
groups, processes for their preparation, and their use
Abstract
An insoluble, only slight swellable, polymer having modified amino groups,
which contain units of the formulae:
##STR1##
or both (I) and (II), wherein R.sup.1, R.sup.2, R.sup.3 and Me are as
defined herein.
| Inventors:
|
Utecht; Jens (Neulussheim, DE);
Rubenacker; Martin (Altrip, DE);
Nilz; Claudia (Rodersheim-Gronau, DE);
Rahm; Rainer (Ludwigshafen, DE)
|
| Assignee:
|
BASF Aktiengesellschaft (Ludwigshafen, DE)
|
| Appl. No.:
|
147804 |
| Filed:
|
March 11, 1999 |
| PCT Filed:
|
August 21, 1997
|
| PCT NO:
|
PCT/EP97/04545
|
| 371 Date:
|
March 11, 1999
|
| 102(e) Date:
|
March 11, 1999
|
| PCT PUB.NO.:
|
WO98/11145 |
| PCT PUB. Date:
|
March 19, 1998 |
Foreign Application Priority Data
| Sep 11, 1996[DE] | 196 36 883 |
| Current U.S. Class: |
526/312; 526/310; 526/318.2; 526/318.3 |
| Intern'l Class: |
C08F 012/28 |
| Field of Search: |
526/310,312,318.2,318.3
|
References Cited
U.S. Patent Documents
| 3424790 | Jan., 1969 | Bond et al.
| |
| 4421602 | Dec., 1983 | Brunnmueller et al.
| |
| 4978427 | Dec., 1990 | Pfohl et al.
| |
| 5430110 | Jul., 1995 | Ahlers et al.
| |
| 5599898 | Feb., 1997 | Hartmann et al.
| |
| Foreign Patent Documents |
| 0 071 050 | Feb., 1983 | EP.
| |
| 0 143 328 | Jun., 1985 | EP.
| |
| 0 216 387 | Apr., 1987 | EP.
| |
| 0 251 182 | Jan., 1988 | EP.
| |
| 0 262 577 | Apr., 1988 | EP.
| |
| 0 264 649 | Apr., 1988 | EP.
| |
| 0 545 383 | Jun., 1993 | EP.
| |
| 0 580 078 | Jan., 1994 | EP.
| |
| 2 303 081 | Jul., 1974 | DE.
| |
| 44 13 720 | Oct., 1995 | DE.
| |
| WO 94/11408 | May., 1994 | WO.
| |
| WO 95/29221 | Nov., 1995 | WO.
| |
Other References
Chemical Abstracts, vol. 1109, No. 16, Oct., 1998, AN 129904w, JP 63 066
205, Mar. 24, 1988.
Patent Abstracts of Japan, vol. 095, No. 006, Jul. 31, 1995, JP 07082320,
Mar. 28, 1995.
Patent Abstracts of Japan, vol. 013, No. 515 (C-655), Nov. 17, 1989, JP 01
207311, Aug. 21, 1989.
|
Primary Examiner: Pezzuto; Helen L.
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier & Neustadt, P.C.
Claims
We claim:
1. An insoluble, only slightly swellable, polymer having modified amino
groups, which contains units of the formulae:
##STR7##
or both (I) and (II), wherein:
R.sup.1 is H or C.sub.1 -C.sub.6 -alkyl;
R.sup.2, R.sup.3 are each H, C.sub.1 -C.sub.20 -alkyl, aryl or aralkyl; and
Me is H or one equivalent of an alkali metal, of an alkaline earth metal or
of ammonium.
2. The insoluble, only slightly swellable, polymer having modified amino
groups of claim 1, wherein R.sup.1, R.sup.2 and R.sup.3 are each H.
3. A process for the preparation of the insoluble, only slightly swellable,
polymer having modified amino groups of claim 1, which comprises reacting
an insoluble, only slightly swellable, polymer which contains units of the
formula (III):
##STR8##
wherein R.sup.1 is H or C.sub.1 -C.sub.6 -alkyl, with (1) an
.alpha.-halocarboxylic acid or an alkali metal, alkaline earth metal or
ammonium salt thereof, or
(2) an aldehyde and hydrogen cyanide or an alkali metal cyanide, or
(3) a cyanohydrin obtained from an aldehyde and alkali metal cyanide; and
hydrolysing the adduct formed.
4. The process of claim 3, wherein from 0.1 to 100% of the units of the
formula (III) which are present in the polymer are converted.
5. The process of claim 3, wherein the reactions are carried out in aqueous
suspension.
6. The process of claim 3, wherein the modification of the units of the
formula:
##STR9##
where R.sup.1 is H or C.sub.1 -C.sub.6 -alkyl, with the formaldehyde and
sodium cyanide is carried out in an aqueous medium.
7. An ion exchanger based on an insoluble, only slightly swellable, polymer
having modified amino groups, which contains units of the formulae:
##STR10##
or both (I) and (II), wherein:
R.sup.1 is H or C.sub.1 -C.sub.6 -alkyl;
R.sup.2, R.sup.3 are each H, C.sub.1 -C.sub.20 -alkyl, aryl or aralkyl; and
Me is H or one equivalent of an alkali metal, of an alkaline earth metal or
of ammonium.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to insoluble, only slightly swellable
polymers having modified amino groups, processes for the preparation of
such polymers and the use of the insoluble, only slightly swellable
polymers having modified amino groups as adsorber resin for metal ions and
ion exchangers.
2. Description of the Background
DE-A-23 03 081 discloses the preparation of water-soluble reaction products
of polyethyleneimine with the sodium salt of chloroacetic acid in aqueous
solution. Water-soluble polyethyleneimines having iminodiacetic acid
groups are obtained. The water-soluble polymers are used as complexing
agents for metal ions.
U.S. Pat. No. 3,424,790 discloses the preparation of water-soluble,
carboxymethylated polyethyleneimines by a multistage process. First,
equivalent amounts of polyethyleneimine are reacted with formaldehyde at
from -15 to 40.degree. C. Thereafter, the adduct is reacted with hydrogen
cyanide or alkali metal cyanides, likewise at from -15 to 40.degree. C.,
and the reaction products are hydrolyzed with alkali metal hydroxides at
from 50 to 110.degree. C. in a subsequent reaction stage. EP-B-071 050
discloses partially hydrolyzed polymers of N-vinylformamide which contains
from 90 to 10 mol % of vinylamine units and from 10 to 90 mol % of
N-vinylformamide units. EP-A-0 216 387 describes copolymers of
N-vinylformamide with other ethylenically unsaturated monomers. The
polymerized N-vinylformamide units can be converted into vinylamine units
by hydrolysis with acids or bases. Polymers containing vinylamine units
are furthermore described in EP-A-0 262 577, EP-A-264 649 and EP-A-0 251
182.
WO-A-94/11408 discloses insoluble, only slightly swellable polymers which
contain polymerized vinylamine units. These polymers are prepared by
polymerizing N-vinylcarboxamides and, if required, other monoethylenically
unsaturated monomers copolymerizable with said N-vinylcarboxamides with,
as crosslinking agents, compounds containing at least two ethylenically
unsaturated double bonds, in the absence of oxygen and polymerization
initiators, to give popcorn polymers, and then hydrolyzing the polymerized
N-vinylcarboxamide units to give vinylamine units by the action of acids,
bases or enzymes. The amino-containing popcorn polymers are used as ion
exchangers or as adsorber resin for metal ions. The polymers described
above and containing N-vinylglycine or N-vinyliminodiacetic acid units are
water-soluble. If they are used as complexing agents for metal ions
dissolved in water, expensive technology is required for separating the
polymeric complexes from the solution.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide novel substances.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
We have found that this object is achieved, according to the invention, by
insoluble, only slightly swellable polymers which have modified amino
groups and contain units of the formulae
##STR2##
where R.sup.1 is H, C.sub.1 -C.sub.6 -alkyl
R.sup.2,R.sup.3 are each H, C.sub.1 -C.sub.20 -alkyl, aryl, aralkyl
Me is H, or one equivalent of an alkali metal, of an alkaline earth metal
or of ammonium.
The present invention furthermore relates to a process for the 35
preparation of insoluble, only slightly swellable polymers having modified
amino groups. In the process, an insoluble, only slightly swellable
polymer which contains units of the formula
##STR3##
where R.sup.1 is H or C.sub.1 -C.sub.6 -alkyl, is reacted with (1)
.alpha.-halocarboxylic acids or alkali metal, alkaline earth metal or
ammonium salts thereof
or
(2) aldehydes and hydrogen cyanide or an alkali metal cyanide or
cyanohydrins obtained from aldehydes and alkali metal cyanide, and
carrying out hydrolysis of the adducts.
The present invention furthermore relates to the use of the insoluble, only
slightly swellable polymers having modified amino groups as adsorber
resins for metal ions and as ion exchangers.
The novel polymers are obtained by a multistage process. First, popcorn
polymers which are insoluble in all solvents and only slightly swellable
therein are prepared by known methods. For this purpose, monomers which
belong to the abovementioned groups (a), (b) and (c) are polymerized.
Monomers of group (a) which are used for the preparation of the known
popcorn polymers are N-vinylcarboxamides of the formula
##STR4##
where R and R.sup.1 are each H or C.sub.1 -C.sub.6 -alkyl.
Suitable compounds of the formula IV are, for example, N-vinyl-formamide,
N-vinyl-N-methylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide,
N-vinyl-N-ethylformamide, N-vinyl-N-n-propyl-formamide,
N-vinyl-N-isopropylformamide, N-vinyl-N-isobutylformamide,
N-vinyl-N-methylpropionamide, N-vinyl-n-butylacetamide and
N-vinyl-N-methylpropionamide. From this group of monomers,
N-vinylformamide is preferably used.
Monomers of group (b), which may be present in the preparation of popcorn
polymers are other monoethylenically unsaturated monomers copolymerizable
with the monomers of groups (a) and (c). These include, for example,
acrylamide, methacrylamide, acrylic acid, methacrylic acid, acrylates,
methacrylates and/or vinyl esters. The acrylates and methacrylates are
preferably derived from saturated, monohydric alcohols of 1 to 4 carbon
atoms or saturated dihydric alcohols of 2 to 4 carbon atoms. Examples of
these esters are methyl acrylate, methyl methacrylate, ethyl acrylate,
ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl
acrylate, isopropyl methacrylate and the esters of acrylic acid and
methacrylic acid which are derived from the isomeric butanols, as well as
hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate,
hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxyisobutyl
acrylate and hydroxyisobutyl methacrylate. Preferred vinyl esters are
vinyl formate, vinyl acetate and vinyl propionate. Other suitable monomers
of group (b) are acrylonitrile, methacrylonitrile, N-vinylpyrrolidone,
N-vinylcaprolactam, 1-vinylimidazole, 2-methyl-1-vinylimidazole and
4-methyl-1-vinylimidazole. The monomers of group (b), alone or as a
mixture with one another, can be polymerized together with the monomers of
groups (a) and (c). Among the monomers of group (b), N-vinylpyrrolidone is
particularly suitable for the preparation of popcorn polymers.
Where they are used in the preparation of the popcorn polymers, the
monomers of group (b) are present in an amount of from 0.1 to 80% by
weight in the monomer mixture comprising (a) and (b).
Compounds which act as crosslinking agents and contain at least two
ethylenically unsaturated nonconjugated double bonds in the molecule are
used as monomers of group (c) in the polymerization. For example,
alkylenebisacrylamides, such as methylenebisacrylamide, and
N,N'-acryloylethylenediamine, N,N'-divinylethyleneurea,
N,N'-divinylpropyleneurea, ethylidene-bis-3-(N-vinylpyrrolidone),
N,N'-divinyl-2,2'-diimidazolylbutane and
1,1'-bis(3,3'-vinyl-benzimidazolin-2-one)-1,4-butane are particularly
suitable. Other suitable crosslinking agents are, for example, alkylene
glycol di(meth)acrylates, such as ethylene glycol diacrylate, ethylene
glycol dimethacrylate, tetraethylene glycol acrylate, tetraethylene glycol
dimethacrylate, diethylene glycol diacrylate, and diethylene glycol
dimethacrylate, aromatic divinyl compounds, such as divinylbenzene and
divinyltoluene, and vinyl acrylate, allyl acrylate, allyl methacrylate,
divinyldioxane, penta-erythrityl triallyl ether and mixtures of the
crosslinking agents. The crosslinking agents are used in amounts of from
0.1 to 10, preferably 1 to 4, % by weight, based on the monomers (a) and
(b) used in the polymerization.
The popcorn polymerization is carried out by known processes, for example
as precipitation polymerization or by mass polymerization. A procedure in
which, as described in EP-B-0 177 812, the popcorn polymerization is
initiated by heating a mixture of from 99.6 to 98.8% by weight of
N-vinylpyrrolidone and 0.4 to 1.2% by weight of a compound having at least
two ethylenically unsaturated double bonds, as crosslinking agent, to 100
to 150.degree. C. in the absence of oxygen and polymerization initiators
is preferred. This polymerization is initiated in particular by the
presence of small amounts of sodium hydroxide solution or potassium
hydroxide solution. A polymerizable popcorn polymer forms within a short
time and, with addition of other suitable monomer mixtures, i.e. the
monomers of group (a) and, if required, (b) and further addition of
monomers (c), initiates the popcorn polymerization of these monomers
without an induction period.
In order to carry out the popcorn polymerization without solvents, the
monomer mixture of (a) and (c) and, if required, (b) is rendered inert by
passing in nitrogen and is then heated to 100-200.degree. C., preferably
150-180.degree. C. It is advantageous to continue passing a gentle stream
of nitrogen through the monomers even during the polymerization. Exclusion
of oxygen is also achieved by polymerizing the batch at a pressure which
is below atmospheric pressure and at which the monomers boil. The
pulverulent popcorn polymers have an average particle size of from about
10 .mu.m to 5 mm, preferably from 10 .mu.m to 500 .mu.m.
Precipitation polymerization in water at monomer concentrations of from 5
to 30% by weight, at from 20 to 200.degree. C. and a pH above 6 is
preferred for the preparation of the popcorn polymers. Further information
on the preparation of the popcorn polymers and hydrolysis of the
polymerized N-vinylcarboxamide units is given in WO-A-94/11408. The
popcorn polymers contain, for example, from 20 to 100% by weight of
N-vinylcarboxamides of the formula IV as polymerized units.
In the hydrolysis, at least 0.5% of the polymerized N-vinylcarboxamides of
the formula IV are hydrolyzed with formation of amino groups. The
hydrolysis is continued until at least the 0.1%, preferably at least 20%,
of the N-vinylcarboxamide units present in the popcorn polymers have been
hydrolyzed. The examples of suitable hydrolysis agents are acids, bases
and enzymes.
Suitable acids are, for example, mineral acids, such as hydrogen halide
(gaseous or aqueous solution), sulfuric acid, nitric acid or phosphoric
acid (ortho-, meta- or polyphosphoric acid) or organic acids, for example
C.sub.1 -C.sub.5 -carboxylic acids, such as formic acid, acetic acid or
propionic acid, or aliphatic and aromatic sulfonic acids, such as
methanesulfonic acid, benzenesulfonic acid or toluenesulfonic acid. In the
hydrolysis with acids, the pH is 0 to 5. From 0.05 to 1.5, preferably from
0.4 to 1.2, equivalents of acid are required per carboxyl radical to be
eliminated in the polymer.
After acidic hydrolysis, the popcorn polymers containing amino functions
are present as a rule as salts, suitable opposite ions being the
corresponding acid anions or anions of the liberated carboxylic acids, for
example formate. For the preparation of the novel water-insoluble
polymers, it is advantageous partially or completely to deprotonate the
polymers in aqueous suspension by adding bases. Particularly suitable
bases are alkali metal and alkaline earth metal hydroxides, in particular
sodium hydroxide, alkali metal and alkaline earth metal carbonates, in
particular sodium carbonate, ammonia and alkyl derivatives of ammonia. The
salts formed in the neutralization, e.g. sodium sulfate, remain in aqueous
solution.
In the hydrolysis with bases, hydroxides of metals of the first and second
main groups of the Periodic Table may be used, for example lithium
hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide,
strontium hydroxide and barium hydroxide. However, ammonia or alkyl and
aryl derivatives of ammonia, for example alkylamines or arylamines, such
as triethylamine, mono-ethanolamine, diethanolamine, triethanolamine,
morpholine, piperidine, pyrrolidine or aniline, are also suitable. In the
hydrolysis with bases, the pH of the reaction mixture is, for example,
from 8 to 14. The bases can be used in the solid, liquid, or, if required,
also gaseous state, diluted or undiluted. Ammonia, sodium hydroxide
solution or potassium hydroxide solution is preferably used. The
hydrolysis in the acidic or alkaline pH range is carried out at from 20 to
170.degree. C., preferably from 50 to 120.degree. C. It is complete after
from about 2 to 8, preferably from 3 to 5 hours. A procedure in which the
acids or bases are added in aqueous solution has proven particularly
useful. After the hydrolysis, neutralization is generally carried out, so
that the pH of the hydrolyzed polymer solution is from 2 to 8, preferably
from 3 to 7. The neutralization is required when it is intended to prevent
or delay the continuation of the hydrolysis of partially hydrolyzed
polymers. For the further processing, the hydrolysis with the aid of bases
has the advantage that an additional neutralization step is superfluous.
The hydrolysis may also be carried out with the aid of enzymes, for example
proteases, ureases or amidases.
The water-insoluble popcorn polymers which contain vinylamine units and are
only slightly swellable may be isolated from the aqueous suspension.
However, it is also possible to carry out the subsequent reaction with
.alpha.-halocarboxylic acids or hydrogen cyanide or alkali metal cyanides
and aldehydes immediately after the hydrolysis.
The novel reaction of the insoluble polymer containing vinylamine units
with .alpha.-halocarboxylic acids takes place unexpectedly smoothly and
quantitatively. Owing to its insolubility in solvents, a chemically and
physically crosslinked polymer should furthermore be attacked by reagents
only with very great difficulty, if at all. However, depending on the
reaction conditions, i.e. the amount of .alpha.-halocarboxylic acid used
or the salts thereof and the reaction medium, reaction time and the
reaction temperature, popcorn polymers having modified amino groups of the
formulae I and II,
##STR5##
where R.sup.1 is H or C.sub.1 -C.sub.6 -alkyl, R.sup.2 and R.sup.3 are
each H, C.sub.1 -C.sub.20 -alkyl, aryl, or aralkyl and Me is H or one
equivalent of an alkali metal, of an alkaline earth metal or of ammonium,
are in fact obtained. Both structure I and structure II may be formed from
primary vinylamine units (R.sup.1 .dbd.H). In the case of secondary
vinylamine units (R.sup.1 .noteq.H) only structure I is possible. Popcorn
polymers having primary vinylamine units (R.sup.1 .dbd.H) are preferably
used as starting materials.
Suitable .alpha.-halocarboxylic acids are all compounds of the formula
##STR6##
where R.sup.2, R.sup.3 are each H, C.sub.1 -C.sub.20 -alkyl, aryl or
aralkyl and Me is H, or one equivalent of an alkali metal, of an alkaline
earth metal or of ammonium and X is halogen, such as F, Cl, Br or I.
Suitable .alpha.-halocarboxylic acids of the formula V are, for example,
chloroacetic acid, bromoacetic acid, iodoacetic acid,
.alpha.-chloropropionic acid, .alpha.-bromopropionic acid,
.alpha.-iodopropionic acid, .alpha.-chlorobutyric acid,
.alpha.-bromobutyric acid, .alpha.-chlorisobutyric acid,
.alpha.-bromocaproic acid, 2-chlorovaleric acid, 2-bromophenyl acetic
acid, 2-chloro-3-phenylpropionic acid, 2-bromo-3-phenylpropionic acid,
.alpha.-chlorolauric acid and .alpha.-bromopalmitic acid. Chloroacetic
acid is preferably used.
The .alpha.-halocarboxylic acids may be used as such or in the form of
their salts. Suitable opposite ions are monovalent or polyvalent metal
ions, for example alkali metal or alkaline earth metal ions. Ammonium ions
or alkyl derivatives thereof, for example methyl-, dimethyl-, trimethyl-
or tetramethylammonium ions or other alkylammonium ions, are also
suitable. Sodium salts are preferably used as starting materials.
Usually, from 0.05 to 5.0, preferably from 0.1 to 2.2, equivalents of
.alpha.-halocarboxylic acid or alkali metal or alkaline earth metal salt
thereof are required per amine unit in the popcorn polymer.
The reaction is carried out in suspension, preferably in a medium in which
the .alpha.-halocarboxylic acid or its salt is soluble. Inert solvents,
e.g. water, methanol, ethanol, isopropanol, ethylene glycol, diethylene
glycol, acetonitrile, acetone, tetrahydrofuran, dioxane,
N-methylpyrrolidone, diethylether, cyclohexane, pentane, benzene or
toluene, and mixtures of the stated solvents are most suitable. The
reaction is preferably carried out in water, methanol, ethanol or a
mixture of these solvents. The polymer content of the suspension is, for
example, from 0.1 to 50, preferably from 1 to 20, % by weight, so that
thorough mixing is ensured during the reaction in order to avoid
agglomeration. A procedure in which the .alpha.-halocarboxylic acid or one
of its salts is added in solution has proven particularly useful. When the
reaction is carried out in an aqueous medium, a pH of from 7 to 12,
preferably from 8 to 10 is established.
The reaction is carried out at from 20 to 180.degree. C., preferably from
50 to 150.degree. C., very particularly preferably from 60 to 110.degree.
C. At temperatures above the boiling point of the reaction medium, the
reaction is carried out under pressure in an appropriate
pressure-resistant container. The reaction time is, for example, from 1 to
30, preferably from 6 to 20 hours. The conversion can be determined, for
example, by quantitative analysis of the halide liberated during the
reaction.
A further possibility for modifying the amino groups in the popcorn
polymers so that insoluble, only slightly swellable polymers having units
of the formulae I and/or II are obtained comprises reacting popcorn
polymers containing polymerized vinylamine units with
aldehydes and hydrogen cyanide or alkali metal cyanides or
cyanohydrins obtained from aldehydes and alkali metal cyanide, and carrying
out subsequent hydrolysis of the adducts in each case.
Suitable aldehydes are, for example, formaldehyde, acetaldehyde,
propionaldehyde, n-butyraldehyde, pentanal, hexanal, heptanal, octanal,
decanal, benzaldehyde and oxo aldehydes, such as C.sub.13 /C.sub.15 oxo
aldehydes or C.sub.9 /C.sub.11 oxo aldehydes. Mixtures of a plurality of
aldehydes may also be used. Formaldehyde is preferably used, usually in
the form of a concentrated aqueous solution. Readily volatile aldehydes
such as formaldehyde and acetaldehyde, can however also be passed in
gaseous form into the reaction mixture.
Examples of suitable alkali metal cyanides are sodium cyanide and calcium
cyanide, sodium cyanide being preferably used. Ammonium cyanide may also
be used.
The reaction is carried out in a medium in which the aldehyde and cyanide
dissolve to a sufficient extent, e.g. water, methanol, ethanol,
isopropanol, n-propanol, n-butanol, ethylene glycol, diethylene glycol,
acetonitrile, acetone, tetrahydrofuran, dioxane or N-methylpyrrolidone, or
mixtures of the stated solvents. The reaction is preferably carried out in
water. The reaction with hydrogen cyanide is carried out, for example, at
a pH of from 0 to 10, preferably from 2 to 6. If, on the other hand,
alkali metal cyanide is used, a pH of, for example, from 8 to 14,
preferably from 10 to 12, is advisable. The polymer content of the
suspension is, for example, from 0.1 to 50, preferably from 1 to 20, % by
weight, so that thorough mixing is ensured during the reaction to prevent
agglomeration.
The aldehyde and hydrogen cyanide or alkali metal cyanide are preferably
used in equimolar amounts, so that 0.1 to 100% of the amino functions
present in the polymer are carboxymethylated. Usually, from 0.15 to 3.0,
preferably from 0.2 to 2, equivalents of aldehydes and alkali metal
cyanides are required per NH.sub.2 group. Excess amounts of aldehyde or
alkali metal cyanide present no problems because they can be readily
separated off from the reaction product. Popcorn polymers having units of
the formula I or II and popcorn polymers which contain units of the
formula I and II are obtained from popcorn polymers having primary
vinylamine units (R.sup.1 .dbd.H), whereas only the units of the formula I
are formed in the case of popcorn polymers having secondary vinylamine
units. Popcorn polymers which are obtainable by polymerizing
N-vinylformamide and have primary amino groups are preferably used as
starting materials.
Reaction may be carried out either continuously or batchwise. As a rule,
aldehydes and hydrogen cyanide or alkali metal cyanide in aqueous
solutions are added to the polymer suspension at from -15 to 100.degree.
C., preferably from 0 to 70.degree. C., and said suspension is then
stirred for some time at from 20 to 180.degree. C., preferably from 50 to
150.degree. C., and very particularly preferably from 60 to 110.degree.
C., to complete the reaction. The reagents may be metered in either all at
once or separately from one another over a period of, for example, 0.5 to
10 hours. The procedure in which the aldehyde and hydrogen cyanide or
alkali metal cyanide are metered in simultaneously in solution is
particularly advantageous, the concentration of cyanide in the reaction
mixture being brought to 1 to 50% above the concentration of aldehyde
during the addition. This means in practice that hydrogen cyanide or
alkali metal cyanide is metered into the polymer at a slightly higher rate
than the aldehyde or, alternatively, cyanide is metered in at the same
rate but before the aldehyde. This suppresses the formation of
by-products.
The reaction can be carried out at atmospheric, superatmospheric or reduced
pressure. The reaction with alkali metal cyanides in the alkali pH range
is preferably carried out under reduced pressure in order to remove from
the reaction mixture the ammonia formed during the hydrolysis. In another
preferred embodiment of the process, an inert gas stream, e.g. air or
nitrogen, is passed through the reaction mixture during the reaction. A
particularly preferred procedure is one which entails simultaneous
stripping with an inert gas and the use of reduced pressure, for example
from 100 to 900, preferably from 500 to 800, mbar. If hydrogen cyanide is
used, the initially obtained cyanoalkylated product is subsequently
hydrolyzed in a second step with the aid of bases, preferably sodum
hydroxide solution. The intermediate may be either isolated or further
processed in the same reaction medium. The hydrolysis is preferably
carried out under reduced pressure whilst stripping with an inert gas. By
repeating the carboxyalkylation reaction, it is possible to increase the
degree of carboxyalkylation of the amino-containing popcorn polymers.
At the end of the reaction, the novel popcorn polymers can be isolated, for
example, by filtration or centrifuging with subsequent washing out of the
salts present with the corresponding suspending agent, preferably with
water or alcohol, and drying in a conventional dryer, such as a
through-circulation dryer or vacuum drying oven, a paddle dryer or a
pneumatic dryer. The polymers are insoluble in water and all known
solvents and furthermore swell only slightly therein.
The insoluble, carboxyl-carrying popcorn polymers are suitable for removing
metal ions from solutions. The type of solvent is not important. However,
the process is preferably applied to aqueous solutions of metal ions, for
example Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+, Al.sup.3+, Ga.sup.3+,
Rb.sup.+, Cs.sup.+, Cu.sup.2+, Ag.sup.+, Au.sup.3+, Fe.sup.2+, Fe.sup.3+,
Ni.sup.2+, Pd.sup.2+, Pt.sup.2+, Co.sup.2+, Rh.sup.2+, Ir.sup.2+,
Cr.sup.3+, Mn.sup.2+, Mn.sup.3+, Zn.sup.2+, Cd.sup.2+, Hg.sup.2+,
Sn.sup.2+ and Pb.sup.2+. The anions of the metal salts have scarcely any
effect on the removability of the metal ions from the solutions. The
amounts of popcorn polymer having units of formulae I and/or II are chosen
so that the number of mols of available carboxyl groups is at least
equivalent to the number of metal ions in the solution. A molar excess of
carboxyl groups is preferably used. For substantial complexing of the
metal ions, from 2 to 100, preferably more than 50, mol % of the carboxyl
functions of the popcorn polymers should be present in deprotonated form.
In an advantageous procedure, the novel popcorn polymer having an
appropriate amount of carboxyl functions is added to a metal salt
solution. However, it is also possible to suspend such popcorn polymers as
free acids in the metal salt solution and to increase the pH of the
solution by adding bases, e.g. sodium hydroxide solution or ammonia, and
thus to deprotonate the carboxyl functions. Marked complexing is
observable in the case of Cu.sup.2+ even at a pH above 5.
The complexing power of the carboxyl-carrying polymers is determined by
quantitative analysis of the metal ions remaining in the solution.
Suitable methods of analysis are, for example, complexometric titration
and atomic absorption spectroscopy or spectralphotometry.
EXAMPLES
Example 1
Popcorn polymer 1
10 g of popcorn polymer having the molar composition of 87.7% of
vinylamine.times.1/2 H.sub.2 SO.sub.4 units, 4.6% of N-vinylformamide
units, 6.6% of N-vinylpyrrolidone units and 1.1% of
N,N'-divinylethyleneurea units (.ident.118 mmol of protonated vinylamine
functions) are suspended in 300 g of water in a stirred apparatus having a
reflex condenser and thermometer. 42.5 g of 97% strength sodium
chloroacetate (.ident.354 mmol) are added and pH is brought to 10 with 49
g of 25% strength aqueous sodium hydroxide solution. The suspension is
then heated at 80.degree. C. for 10 hours with thorough stirring. After
cooling to room temperature, the solid is filtered off with suction,
washed several times with water and dried for 24 hours at 100.degree. C.
and 100 mbar in a vacuum drying oven. 17.8 g of carboxymethylated popcorn
polymer having 73.7 mol % of units of the structure I (R.sup.1, R.sup.2,
R.sup.3 .dbd.H, Me.dbd.Na) and 14.0 mol % of the structure II (R.sup.2,
R.sup.3 .dbd.H, Me.dbd.Na) are obtained.
Example 2
Popcorn polymer 2
10 g of a popcorn polymer having a molar composition of 73.4% of
vinylamine.times.1/2 H.sub.2 SO.sub.4 units, 8.1% of N-vinylformamide,
17.4% of N-vinylpyrrolidone units and 1.1% of N,N'-divinylethyleneurea
units (.ident.93 mmol of protonated vinylamine functions) are reacted with
39 g of 97% strength sodium chloroacetate (.ident.325 mmol) and 45 g of
25% strength aqueous sodium hydroxide solution, as described in Example 1.
16.5 g of carboxymethylated popcorn polymer having 78.0 mol % of units of
the formula I (R.sup.1, R.sup.2, R.sup.3 .dbd.H, Me.dbd.Na) and 22.0 mol %
of units of the formula II where R.sup.2 and R.sup.3 are H and Me is Na
are obtained.
Example 3
Popcorn polymer 3
10 g of a popcorn polymer having a molar composition of 56.0% of
vinylamine.times.1/2 H.sub.2 SO.sub.4 units, 4.2% of vinylformamide, 38.5%
of N-vinylpyrrolidone units and 1.3% of N,N'-divinylethyleneurea units
(.ident.64.1 mmol of protonated vinylamine functions) are reacted with
30.8 g of 97% strength sodium chloroacetate (.ident.256.4 mmol) and 24 g
of 25% strength aqueous sodium hydroxide solution as described in Example
1. 14.4 g of carboxymethylated popcorn polymer having 44.8 mol % of units
of the formula I where R.sup.1, R.sup.2, R.sup.3 are H and Me is Na and
11.2 mol % of units of the formula II where R.sup.2 and R.sup.3 are H and
Me is Na are obtained.
Example 4
Popcorn polymer 4
10 g of a popcorn polymer having a molar composition of 29.7% of
vinylamine.times.1/2 H.sub.2 SO.sub.4 units, 4.1% of N-vinylformamide,
64.8% of N-vinylpyrrolidone units and 1.4% of N,N'-divinylethyleneurea
units (.ident.30.3 mmol of protonated vinylamine functions) are reacted
with 14.7 g of 97% strength sodium chloroacetate (.ident.122 mmol) and 10
g of 25% strength aqueous sodium hydroxide solution as described in
Example 1. 11.6 g of carboxymethylated popcorn polymer having 21.6 mol %
of units of the formula I where R.sup.1, R.sup.2, R.sup.3 are H and Me is
Na and 8.1 mol % of units of the formula II where R.sup.2 and R.sup.3 are
H and Me is Na are obtained.
Example 5
Popcorn polymer 5
25 g of popcorn polymer having the molar composition of 87.7% of 30
vinylamine, 4.6% of N-vinylformamide units, 6.6% of N-vinylpyrrolidone
units and 1.1% of N,N'-divinylethyleneurea units (439 mmol of vinylamine
functions) are suspended in 770 ml of water in a stirred apparatus
equipped with a reflux condenser, two dropping funnels and a thermometer.
First 26 g (95 mmol) of 99% strength hydrocyanic acid and then, in the
course of 1 hour, 95 g (950 mmol) of a 30% strength formaldehyde solution
are added dropwise at 20.degree. C. The reaction mixture is stirred for 48
hours at 40.degree. C. After filtration with suction, washing with water
and drying, 55 g of a cyanomethylated product are obtained. This is taken
up in 160 g of 10% strength aqueous NaOH and stirred for 36 hours at
95.degree. C. while passing through nitrogen and from 800 to 900 mbar
until no further ammonia escapes from the reaction mixture. After cooling
to room temperature, the solid is filtered off, washed several times with
water and dried for 24 hours at 100.degree. C. and 100 mbar in a vacuum
drying oven. 80 g of carboxymethylated popcorn polymer having 24 mol % of
units of the formula I where R.sup.1, R.sup.2, R.sup.3 is H and Me is Na
and 66 mol % of units of the formula II where R.sup.2, R.sup.3 are H and
Me is Na are obtained.
Use Examples
To investigate the complexing power, different amounts of the finely ground
popcorn polymers 1 to 4 described above are added to 100 g of each of the
stock solutions stated below, each of which contains 60 mg of the metal
ion stated in the table. The suspension is stirred for 1 hour at room
temperature, after which the metal ion content of the solution is
determined by complexometric titration with Titriplex III solution. The
results are shown in Table 1.
______________________________________
Stock solutions:
______________________________________
CuSO.sub.4 1.5537 g per l of aqueous solution
NiSO.sub.4 . 6H.sub.2 O 2.7952 g per l of aqueous solution
ZnSO.sub.4 . 7H.sub.2 O 2.6694 g per l of aqueous solution
Hg(NO.sub.3).sub.2 . H.sub.2 O 5.0179 g per l of aqueous solution
CaCl.sub.2 . 2H.sub.2 O 2.2114 g per l of
aqueous solution
MgCl.sub.2 . 6H.sub.2 O 5.0179 g per l of aqueous solution
______________________________________
TABLE 1
______________________________________
Complexing power of the popcorn polymers 1 to 4
Decrease in concentration [%]
Popcorn Popcorn
Popcorn
Popcorn
Polymer polymer polymer polymer polymer
Metal ion [g] 1 2 3 4
______________________________________
Cu.sup.2+
0.1 38 33 26 18
0.6 100 100 100 57
2.0 100 100 100 100
Ni.sup.2+ 0.1 28 30 17 9
0.6 100 100 84 38
2.0 100 100 100 96
Zn.sup.2+ 0.1 30 33 20 9
0.6 97 97 96 43
2.0 98 98 96 97
Hg.sup.2+ 0.1 85 91 60 34
0.6 93 93 92 92
2.0 94 94 94 93
Ca.sup.2+ 0.1 19 18 14 6
0.6 97 93 61 23
2.0 99 98 98 67
Mg.sup.2+ 0.1 14 13 9 6
0.6 65 60 38 15
2.0 98 98 98 43
______________________________________
Top